diff --git a/src/cmd/compile/internal/types2/decl.go b/src/cmd/compile/internal/types2/decl.go
index 178bebe2ec..4966f19892 100644
--- a/src/cmd/compile/internal/types2/decl.go
+++ b/src/cmd/compile/internal/types2/decl.go
@@ -602,7 +602,11 @@ func (check *Checker) typeDecl(obj *TypeName, tdecl *syntax.TypeDecl, def *Named
 	if alias {
 		// type alias declaration
 		if !check.allowVersion(obj.pkg, 1, 9) {
-			check.error(tdecl, "type aliases requires go1.9 or later")
+			if check.conf.CompilerErrorMessages {
+				check.error(tdecl, "type aliases only supported as of -lang=go1.9")
+			} else {
+				check.error(tdecl, "type aliases requires go1.9 or later")
+			}
 		}
 
 		obj.typ = Typ[Invalid]